Paradoxical reactions and biologic agents: a French cohort study of 9303 patients.

The likelihood of PRs was associated with IBD or a combination of a least two inflammatory diseases. More studies are needed to assess the benefit of systematically adding csDMARDs for such high-risk patients. What is already known about this topic? Most published studies about paradoxical reactions concern paradoxical psoriasis in patients receiving anti-tumour necrosis factor-α agents. Few data are available for other paradoxical reactions and the most recent biologics. What does this study add? Risk of paradoxical reactions was increased with inflammatory bowel disease and a combination of at least two inflammatory diseases. Risk of paradoxical reactions was reduced with conventional synthetic disease-modifying antirheumatic drugs or corticosteroid therapy, which could be added for high-risk patients.